I am trying to learn how to work with multiple Datasources in Spring Boot.
I was able to create MultiRoutingDataSource and loaded with Datasources that were configured in application.properties. Here are some code snippets. Full code is at https://github.com/ivoronline/springboot_db_multitenant_dingleentity_shcemaparamtersfromtable

application.properties

# SCHEMA1
schema1.spring.datasource.jdbc-url = jdbc:oracle:thin:@localhost:1522/orcl
schema1.spring.datasource.username = SCHEMA1
schema1.spring.datasource.password = LETMEIN

SchemaConfig

@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
  basePackages            = "com.ivoronline.springboot_db_multitenant_dingleentity_shcemaparamtersfromtable.schema.repository",
  entityManagerFactoryRef = "multiEntityManager",
  transactionManagerRef   = "multiTransactionManager"
)
public class SchemaConfig {

  //PROPERTIES
  private final String ENTITY_PACKAGE = "com.ivoronline.springboot_db_multitenant_dingleentity_shcemaparamtersfromtable.schema.entity";
  
  //=========================================================================================================
  // SCHEMA 1 DATA SOURCE
  //=========================================================================================================
  @Primary
  @Bean
  @ConfigurationProperties("schema1.spring.datasource")
  public DataSource schema1DataSource() {
      return DataSourceBuilder.create().type(HikariDataSource.class).build();
  }
  //=========================================================================================================
  // MULTI ROUTING DATA SOURCE
  //=========================================================================================================
  @Bean
  public MultiRoutingDataSource multiRoutingDataSource() {
  
      Map<Object, Object> targetDataSources = new HashMap<>();
                          targetDataSources.put(1, schema1DataSource());
                          targetDataSources.put(2, schema2DataSource());
                          //targetDataSources.put(3, schema3DataSource());
      
      MultiRoutingDataSource multiRoutingDataSource = new MultiRoutingDataSource();
                             multiRoutingDataSource.setDefaultTargetDataSource(schema1DataSource());
                             multiRoutingDataSource.setTargetDataSources(targetDataSources);

      return multiRoutingDataSource;
  }

But instead of hard coding connection details in application.properties I would like to take them from Database. For that purpose I have configured another configuration file, Tenant Entity, TenantRepository that just holds name and password for each Schema. But I don’t how to put those Tenants into MultiRoutingDataSource. If I put @Autowired TenantRepository tenantRepository; inside above SchemaConfig.java I get circular Bean reference and can’t use tenantRepository inside multiRoutingDataSource().

If I try to set new setTargetDataSources() inside Control it still doesn’t work.

MyController

@RestController
public class MyController {

  //PROPERTIES
  @Autowired PersonRepository personRepository;
  @Autowired TenantRepository tenantRepository;
  @Autowired @Qualifier("multiRoutingDataSource") MultiRoutingDataSource multiRoutingDataSource;
  //=========================================================================================================
  // MIX STATEMENTS
  //=========================================================================================================
  @ResponseBody
  @GetMapping("/Set")
  public String set() {
    Map<Object, Object> targetDataSources = new HashMap<>();
                        targetDataSources.put(3, dataSource3());
    multiRoutingDataSource.setTargetDataSources(targetDataSources);
    return "OK";
  }
  
  //=========================================================================================================
  // DATA SOURCE
  //=========================================================================================================
  public DataSource dataSource3() {
    DriverManagerDataSource dataSource = new DriverManagerDataSource();
                            dataSource.setUrl            ("jdbc:oracle:thin:@localhost:1522/orcl");
                            dataSource.setUsername       ("SCHEMA3");
                            dataSource.setPassword       ("LETMEIN");
                          //dataSource.setDriverClassName("oracle.jdbc.OracleDriver");
    return dataSource;
  }

}